Preparation and biological evaluation of ZrO2 all-ceramic teeth by DLP technology

Photosensitive ZrO2 suspensions for stereolithography

A first-principles study of the properties of four predicted novel phases of AlN

Aluminum nitride (AlN) is a promising material for heat sinks and microelectronic applications because of the advantages of high theoretical thermal conductivity, high mechanical strength, good electrical insulation, low dielectric constant and low thermal expansion coefficient. However, the difficulties in shaping complex-shaped parts with a high thermal conductivity have retarded the wide applications of AlN ceramic. Herein, we design a new binder system containing resin components and adopt the powder injection molding technology to fabricate complex-shaped AlN parts. After the debinding process, the special binder system would produce residual carbon, which could react with Al2O3 and result in decreasing oxygen impurity and forming the yttrium-rich aluminates. The yttrium-rich aluminates can accelerate the densification of AlN ceramic and fasten the oxygen on the triangular grain boundary, leaving the clean grain boundary beneficial for high thermal conductivity. The as-prepared AlN parts with complex shape possess a high thermal conductivity of 248 W m−1 K−1.

Powder injection molding of complex-shaped aluminium nitride ceramic with high thermal conductivity

The porous bioceramic scaffolds require favorable mechanical properties and excellent bioactivity to promote bone repair. In this work, 45S5 bioglass® & biphasic calcium phosphate (BCP) bioceramic scaffolds with a diamond lattice structure (porosity of 70%) were manufactured accurately by digital light processing (DLP). After optimizing the solid loading of bioceramic suspension to 40 vol%, scaffolds with the minimum pore size of 400 µm were fabricated successfully under exposure energy of 12.54 mJ/cm2. In the initial stage of sintering, crystallization occurred during 45S5 bioglass® itself, bioglass also promoted hydroxyapatite (HA) decomposition to tricalcium phosphate (TCP). With extending holding time to 4 h, Si4+ from 45S5 bioglass® diffused into TCP to produce Ca5(PO4)2SiO4, which could enhance the compressive strength of bioceramic scaffolds. Meanwhile, bioglass would assist the growth and roughening of ceramic grains because of the ion-diffusion from bioglass to BCP. However, as holding time extended to 6 h, abnormal grain growth and cracks occurred which would decrease compressive strength. The best value of compressive strength is 1.735 MPa at the holding time of 4 h. 45S5 bioglass® also accelerated ion exchange such as Si4+ and CO32- between bioceramic and SBF solution. This kind of bioceramics may be used as bioactive scaffolds with customizable fine structures and provide potential applications in bone tissue engineering.

Liya Shen

Papers

Aluminum nitride shaping by non-aqueous gelcasting of low-viscosity and high solid-loading slurry